AS if Peter Jackson weren’t busy enough finishing his remake of “King Kong,” due next month, he has found the time to painstak ingly reconstruct a legendary lost sequence from the 1933 original.

Included as part of the copious extras on the Nov. 22 DVD debut of “King Kong” is Jackson’s version of the famous “spider-pit” sequence, which co-director Merian C. Cooper cut from the 1933 classic before its release.

Cooper wrote in a memo that the sequence – which came after the scene where Kong shook four sailors off a log bridge and into a ravine – “stops the movie,” and some historians believe he actually burned the footage, which was considered too horrific for 1930s audiences.

But a handful of photographs and sketches survive, along with the original script – and the sequence has become a Holy Grail for hard-core Kong fans.

These include Jackson, who had the clout and the backing of Warner Home Video to do his own version – using vintage stop-motion techniques to create black-and-white footage that is virtually indistinguishable from the original.

“Peter is obsessed with the missing spider-pit sequence,” says fellow director Frank Darabont, who along with fellow Kong fanatic Rick Baker (who played King Kong in a suit of his own design in the 1976 remake) helped Jackson analyze the original script and how it could be translated to film in period style.

About 30 minutes of a new 140-minute documentary on the making of “King Kong” on the DVD are actually devoted to the production of the missing sequence.

This required constructing miniature models of creatures and sets and combining them – using archaic methods like rear-screen projection – with new live-action footage in which members of Jackson’s Weta Workshop staff play members of Carl Denham’s crew.

“I don’t regard this sequence as serious historical archeology,” Jackson says modestly. “Most of it is guesswork . . . us being King Kong fans.”

The new footage is not integrated into the entire original film, but about three minutes of it is presented as part of a six-minute excerpt that includes footage from 1933.

The new scenes actually begin before the crew arrives at the log bridge.

We see, for the first time, that the terrified sailors are fleeing a styracosaurus, a dinosaur that ended up on the cutting-room floor in 1933. (Jackson owns the original model, which was used in “Mighty Joe Young,” and it was X-rayed so a new puppet could be constructed and manipulated, frame by frame, by hand.)

After Kong shakes them off the log in old footage, the screaming crew members now ineffectually battle – and are consumed by

– a quintet of fearsome creatures.

These include a giant spider, a massive crab-like creature, a tentacled beast, a crocodile-like creature – and the giant lizard who appears in the original film slithering up from the ravine on a vine, which is cut by Jack Driscoll.

Even though the special effects (and the acting) are comparatively primitive and a little campy by contemporary standards, the new footage is surprisingly scary – a reverent homage that’s very much of a piece with the original.